Population Dynamics

LEARNING OBJECTIVES Describe interactions within and among populations. Explain carrying capacity, limiting factors, and population growth patterns. Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Population Dynamics Population: all the individuals of a species that live together one area at one time. Demography: the statistical study of populations, make predictions about how a population will change. Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Population Dynamics Three Key Features of Populations Size Density Dispersion Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Three Key Features of Populations 1. Size: the number of individuals in an area Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Three Key Features of Populations Growth Rate: Birth Rate (natality) - Death Rate (mortality) Birth rate (b) − death rate (d) = rate of natural increase (r). Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Three Key Features of Populations 2. Density: the measurement of population per unit area. Formula: D = n / S Population Density = of individuals divided by the unit of area. Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Factors that affect density 1. Immigration- movement of individuals into a population 2. Emigration- movement of individuals out of a population

Factors that affect density 3. Density-dependent factors- Biotic factors in the environment that have an increasing effect as population size increases   E.g. competition disease habitat availability

Factors that affect density 4. Density-independent factors - Abiotic factors in the environment that affect populations regardless of their density   E.g. rising temperatures drought habitat destruction

Factors That Affect Future Population Growth Immigration + + - Population Mortality Natality - Emigration

Three Key Features of Populations 3. Dispersion: describes individuals’ spacing relative to each other. clumped even or uniform random Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

Population Dispersion

Other factors that affect population growth Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment. E.g. Amount of water Amount of food Temperature

Other factors that affect population growth Carrying Capacity- the maximum population size that can be supported by the available resources There can only be as many organisms as the environmental resources can support Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

J-shaped curve (exponential growth) Carrying Capacity Nu m b e r J-shaped curve (exponential growth) Carrying Capacity (k) S-shaped curve (logistic growth) Ok so Time